Radio-frequency identification (RFID)-based tracing is becoming increasingly common in many fields of trade and industry. Although many industrial sectors have utilized tracing systems, covering the product chain from the supplies of raw materials to the final products in the market, the forestry and wood sector is still in the beginning of this process partly due to a complicated supply chain structure. The nature of logging operation itself, logistics of the forest industry, environmental factors, needs of the user of the logs and the demanding electromagnetic properties of wood set special requirements for the transponder application process and transponders itself, only to mention some aspects. The general objective in this sector is to develop methodology and advanced technologies that can improve the use of wood and optimize the forest production through the chain of transformation, minimizing environmental impacts (www.indisputablekey.com).
Two main types of RFID transponders (tags) are known that can be used for marking logs (http://www.indisputablekey.com/transponder_applicator.php): a patch type transponder, which is inserted into a slot or groove machined into the log, and a nail type transponder, which is inserted into a hole drilled into the wood or hammered directly into the wood. Patch transponders typically have the form of a rectangular slab. Further examples of known marking devices are known from FR 2673026, FR 2885723, FR 2913134, and FR 2810436, which disclose a devices that can be inserted into wood and separate transponders, which can be inserted and removed to and from a separate space of the device reserved for that purpose. Thus, the transponders are not integral parts of the device, which makes their use unnecessarily complex.
It would be beneficial in many applications that the transponder would not need to be removed from the wood product before further processing of the wood, such as pulping, paper making, burning or composting. Thus, the transponders should contain as little non-biodegradable materials as possible.